The present invention relates to an apparatus for spraying of liquids. More particularly, the present invention is directed to a roadside spraying apparatus which minimizes atomization and resulting drift of sprayed herbicides or other liquids, mounted on a detachable frame fixed to a vehicle, and controllable by the operator of the vehicle by means of a control panel, which panel regulates the flow of the liquids as well as the direction in which the liquids are sprayed.
Many state highway departments, counties and cities, have for several years been mechanically cutting undesirable weeds, grass and brush in their right-of-ways. However, while such cutting has been primarily accomplished by hand labor or mechanical means, it can be costly and time consuming. In order to minimize these problems, many publicly funded organizations have attempted to spray their right-of-ways with herbicides that would control the undesirable plant growth.
Herbicides used primarily for control of broadleaf weeds and some unwanted grasses are used extensively on the right-of-way, leaving desirable grasses alive for erosion control. These herbicides, such as MSMA and 2-4-D, are termed selective since they do not kill the desirable grasses. Other herbicides used primarily for control of vegetation on shoulders and in the roadway are intended to kill all vegetation and hopefully prevent its regrowth for some period of time. Such herbicides are termed residuals. Other liquids, including fertilizers, may also be advantageously applied along a roadway; however, since application of liquid herbicides is more common, Applicant concentrates this discussion upon the application of herbicides.
Such application almost invariably involves spraying a liquid from an apparatus comprising some type of nozzle. As liquid is sprayed from a moving nozzle, it is generally applied to strip-like areas of ground called swaths. A swath, in this context, also refers to the spray pattern produced by the nozzle and applied to the corresponding strip of ground.
The equipment which has been used for roadside spraying of herbicides in the past has generally been of three common types. Handgun-type sprayers are still in common use today for lack of anything with more versatility. Another common type of equipment comprises a long boom extending out from the side of the vehicle and across the right-of-way. An example of such a long boom is shown in U.S. Pat. No. 2,995,307 issued to J. J. McMahon. Another has been the use of an off-center nozzle mounted to the side of the truck. The use of the off-center nozzle is discussed further below.
The long-extending boom has been used widely because of its ability to reach 25 to 30 feet into the right-of-way. Some designs have provided the boom in sections to give the operator more flexibility as to where he could spray the herbicide. This has also allowed the operator to save chemicals. This type of unit, however, does not lend itself to many right-of-way applications because of hills, back slopes and obstructions in the areas to be sprayed. Common obstructions including trees, bluffs, road signs and the like are a major problem. The extended boom is vulnerable to contact with such obstructions causing extensive down time and delays accompanied by losses in production. It is also very expensive to replace such booms.
Hydraulic cylinders mounted along the extended boom can be utilized for raising the boom over obstructions but may make herbicide application even more cumbersome. Upon encounter obstructions, the driver may have to slow the speed of the vehicle to raise the boom. The slower vehicle speeds will likely be accompanied by increased concentration of applied herbicides. The raising of the boom, furthermore, increases the distance which the herbicide must be sprayed before contacting the roadside area at which it is targeted. This increase in distance consequently decreases the precision of the application since there is a greater chance that wind and other natural forces will cause the herbicide to drift off-target. The uniformity of the herbicide application may likewise be affected. In some situations, it is necessary to use two operators to operate a long-boom sprayer. This increases the costs due to the extra labor required. Also, long boom apparatuses generally require the vehicle to have greater gross vehicle weight since an extended spray boom may require heavier axles and generally heavier duty vehicles for support.
The off-center nozzle, in many cases, has advantages over the long booms. The operator of the off-center nozzle can spray without worrying about obstructions in the right-of-way except for those immediately beside the vehicle. In the event that protective measures are not taken to guard against such immediately adjacent obstructions, however, damage to the nozzle can occur upon encountering an obstacle immediately adjacent the roadway. The off-center nozzle can be mounted anywhere to the side of the vehicle and the spray pattern can cover an area beginning immediately beside the truck and extending from 10 to 30 feet out into the right-of-way. Wind velocity tends to dramatically affect the distance, however, and in such circumstances the spray might not extend past 10 to 15 feet from the vehicle. This type of nozzle also does not give the operator much versatility to place a herbicide only in selected areas existing across the right-of-way. In practice, the weeds are often in spotted areas lying 20 to 40 feet away from the spray truck and the operator has no way to get the herbicide to the target, especially if the wind velocity overpowers the spray. The operator also, in certain situations, needs to spray the herbicide beyond undesirable, taller growing vegetation, but the taller vegetation might prevent the spray from reaching the vegetation beyond. This may cause excessive amounts of herbicide to be unnecessarily used, which may increase the costs of the spraying program and may also overtreat some of the vegetation causing undesirable results.
The same problems also exist with controlling undesirable brush. A long extending boom is not often used for this purpose. Generally, the use of a handgun and the off-center spraying means are used in such situations. Spotted applications to the soil under the undesirable brush with the use of a handgun, spraying specially selected herbicides, provide easy control of brush. In such situations, rain carries the chemical herbicide into the root zone to be picked up by the brush. The herbicide can subsequently interfere with the natural processes in the plant causing its ultimate death. However, spotted application of such herbicides by handguns is slow, which increases application cost and, in most cases, the herbicide is overapplied, resulting in excessive killing of low growing desirable ground cover.
With the development of new herbicides, especially new selective herbicides, it has become more important to eliminate the problem encountered with extended booms, off-center nozzles and handguns. In the case of certain chemicals, it is necessary to apply them from 1 to 11/2 quarts per acre or 43,560 square feet. In the case of other currently used chemicals, it is necessary to apply them at 4 to 8 ounces to control more susceptible tall growing vegetation. Greater amounts of these herbicides and others may kill or damage desirable vegetation and may consequently leave partially to totally bare ground. Such problems often prevent many highway departments, counties and cities from going into vegetation management programs with the new herbicides to eliminate the more costly program of hand labor and mechanical cutting. It is, therefore, an object of the present invention to provide for controlling the composition and concentration of herbicides during their sprayed application. Concentration, in this context, refers to the amount of herbicide sprayed per unit area of ground while composition refers to the type or types of herbicide.
Furthermore, as the concentration of the herbicide applied at each elemental target area is critical, controlling the uniformity of the application is advantageous. Poorly controlled, non-uniform applications result in greater concentrations being applied to some elemental target areas than others. This forces a herbicide treatment program to be limited by the effects of the greater elemental concentrations in order to avoid adverse effects of over-treatment at those elemental areas. The resulting quality of the overall herbicide treatment program is thus constrained and must fall short of optimization. It is, accordingly, an object of the present invention to provide an apparatus for roadside application of herbicides while also controlling the uniformity of the application.
In many applications it is also advantageous to apply different herbicides or different concentrations of herbicides to locations at different distances from the roadside. For instance, it may be desired to apply a herbicide to an area immediately adjacent to a roadway which will kill all vegetation. At areas further from the roadway, however, it may be desired to apply a selective herbicide to kill broadleaf weeds but leave low growing grass unharmed. Furthermore, an operator of a roadside spraying apparatus will want to apply different herbicides to different areas as roadside vegetation changes during a single pass. Therefore, any roadside spraying apparatus allowing the application of different herbicides to different areas must not have any time lags between the time of the decision to apply a different herbicide and the time of the actual application of that herbicide. Therefore, it is an object of one embodiment of the present invention to enable an operator to apply different herbicides in different swaths with little or no time delay.
Additionally, when applying herbicides, it is often critical to confine the application to the area which is intended to be treated in order to avoid undesirable effects on adjacent vegetation, waterways, livestock, or other items which are not targets of the herbicide treatment. Previous spraying apparatuses utilize angle spray nozzles which spray liquid in an atomized spray. Such atomization enables uniformity of treatment and treatment of greater areas per single nozzle; however, in the process of atomization, various sized liquid droplets are randomly created. The smaller sized liquid droplets tend to drift beyond the area of application, and undesirable effects may result. The present invention is directed at minimizing this problem of drift without sacrificing uniformity and while optimizing other advantageous characteristics of a roadside sprayer.
By spraying liquid herbicide in aerial streams, some prior art has minimized such atomization and drift. For the purposes of this invention, aerial streams are airborne streams of liquid which are virtually unaccompanied by atomized droplets. Nozzles which spray liquids in such aerial streams are called straight stream nozzles, or zero degree angle nozzles. Stream spraying, unfortunately, creates problems of uniformity and breadth of possible application. For instance, an unmodified single stream being sprayed from a moving vehicle would apply liquid to only a very narrow streak along the roadside. Multiple streams enable application to broader roadside areas, but tend to apply liquid nonuniformly in multiple parallel narrow streaks along the roadside. Uniform application of herbicides is necessary in order to optimize performance and economic considerations of a roadside spraying operation. Such streaked application produces nonuniform concentrations of the herbicide and, thus, diminishes the desired effect of the herbicide. Other inventions have attempted to address this problem by rapidly altering the direction of aerial streams but have fallen short of the goal of uniform application for numerous reasons. It is, therefore, another object of the present invention to provide an apparatus and method for applying liquid uniformly to a broad roadside while minimizing atomization and drift.
It is also an object of the present invention to provide a method and apparatus for spraying liquid in multiple aerial streams which are scattered in a manner that optimizes uniformity of the application of the liquid on a roadside throughout the course of application and across the breadth of the targeted roadside.
As right-of-ways may be quite broad, it is another object of the present invention to provide vehicle mountable apparatus for spraying herbicide onto swaths along a roadway, which apparatus maximizes the width of an aggregate swath treatable at one time.
It is yet another object of the present invention to provide for protection of a roadside spraying apparatus when encountering an obstruction along a roadway.